tashaboot: arm64 bringup, semihosting payload loader

consoles on the pl011 the dtb points at, walks the memory node and
chosen, loads an arm64 kernel Image over semihosting and jumps to it
with the documented register state. string functions, printf and
libfdt are vendored from lk (lk2nd) and u-boot so the libc surface is
the one those projects already proved. built and booted on qemu virt,
payload exits clean through semihosting.

1 files changed, 33 insertions, 0 deletions

diff --git a/dts/qemu-virt.dts b/dts/qemu-virt.dts
new file mode 100644
index 0000000..09a4609
--- /dev/null
+++ b/dts/qemu-virt.dts
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * qemu virt board dtb for tashaboot. mirrors the machine qemu actually
+ * builds, address cells and all, so the dtb walk sees the same reg
+ * shapes as any real board's blob.
+ */
+
+/dts-v1/;
+
+/ {
+	model = "QEMU virt";
+	compatible = "qemu,virt", "arm,virt";
+	#address-cells = <2>;
+	#size-cells = <1>;
+
+	chosen {
+		stdout-path = "/pl011@9000000";
+		bootargs = "earlycon=pl011,0x09000000 console=ttyAMA0";
+	};
+
+	memory@40000000 {
+		device_type = "memory";
+		reg = <0x0 0x40000000 0x4000000>;
+	};
+
+	pl011@9000000 {
+		compatible = "arm,pl011", "arm,primecell";
+		reg = <0x0 0x09000000 0x1000>;
+		current-speed = <115200>;
+		clock-frequency = <24000000>;
+		status = "okay";
+	};
+};